Microphone support



` B. vF. RYAN MICROPHONE SUPPORT -Filed 0cm 5, 1938 Mach 1s, 1941.

Patented Mar. 18, 1941 PATENT OFFICE IVIICRO'PHONE SUPPORT Byron F.Ryan, L'os Angeles, Calif., assigner to Warner Brothers Pictures, Inc.,a corporation of Delaware Application October 3, 1938, Serial No.232,989

4 Claims.

'This invention relates to sound-wave detecting apparatus such asmicrophones and parti-cularly to a mounting for such apparatus. Thismounting has been designed for use on the end of .a boom used on motionpicture sets wherein the microphone is suspend-ed above, or proximateto, the source of sound and moved by the boom to follow ythe soundsource.

In the use of a sensitive microphone o-n the end of a boom it becomes aproblem to prevent extraneous sounds, caused by the vmovement of themicrophone, from being detected and Itransmitted to the sound record.Generally, the boom ann is quite long and flexible, and vibrations aresometimes introduced therein broth vertically and horizontally, causedby movement of the boom or microphone at the end thereof.

.The mounting is in the form of a mechanical lter which is adjustable sothat it may be tuned to eliminate certain frequencies, and is of a.shape so as not to interfere with proper functioning of .themicrophone. The mount is a `combination filter system which eliminatesboth high and low frequencies.-

An object ofthe present invention, therefore, is to minimize the effectsof moving a boom with a microphone .suspended .thereon during the soundpick-up operation.

Another object of the invention is to mount a microphone so that it maybe .spatially adjusted without its being electrical-1y affected.

A fur-ther object of the invention is to provide a mechanical filtermounting for eliminating mechanical vibrations .of different frequenciesintroduced by movement of the microphone.

A YfurtherA .object of the invention is to enable a mechanical ltermounting to be tuned -fior different loads.

Although the novel features which are believed to be characteristic ofthis invention are pointed out with particularity in the claims appendedherewith, the manner of its organization and the mode of its operationwill be better understood by referring .to the following descriptionread in conjunction with the accompanying drawing forming a partthereof, in which Figur-e 1 is .a partial cross-sectional View of themicrophone mounting as attached to Ia microphone boom;

Figure 2 is a cross-sectional view of t-he low frequency filter portionof the mounting taken Ialong the 'line 2-2 of Fig. 1; and

Figure 3 is a plan view of the high frequency portion of .the filtermounting .taken along the line 3-3 of Fig. 1.

Referring now to the drawing, in which the same numerals indicateidentical element-s, the end `5 of a microphone boom has connectedthereto, by .an 'adjustable coupling 6, a rod 'I having -a flanged lowerendi 8. The element 5 may be .the extendible end oi the adjustable{crossarm of the boom shown in W. A. Mueller Patent 2,122,778 of July.5,1938. Rotatably mounted on the rod 'I is a cap or ycover lll having lagroot/ed 'or pulley portion I.I, .around which is a cable `I3, one endof which is attached in an eye-bolt I5 on the portion I'I. Fastenedtothe upper side of the pulley section by screws I6 isa cylindricalhousing IB to which is also fastened one end of a coil spring I9 atpoint 20. The other end of the coil spring I9 is attached to a collar2`2 at 23, .the collar 22 being pinned to the rod I by a vpin 24. Thisarrangement permits the cover .,IIl .to be rotated in one directionabout the rod 'I when the cable I3 is pulled, and to be rotated in theother direction by the tension of spring I9 when .the cab-le I3 isreleased. This mechanism permits 'the rotation of the microphone by theboom operator.

Attached to .the cover` Ill by screws 26 is a conical-shaped shell 2l inwhich are elongated slots 28, `the purpose of which will be explained.hereinafter. Within the shell 2l is a fine-grained sponged .rubberconforming to the shape :of the shell and made up of .two `sections. 30and 3|. C

Section 30 of the rubber has a hole therein to accommodate the shaft end33 off a yoke member y32.l The shatt 33 has a stud 4l] threaded therein.In the upper end of :the shaft 33 there are threaded' three radiallyextending bronze arms v.34, 35 and 36 (see Fig. 2), in the .slotted endsof 'which are inserted iin members 3l, 38 and 39, respectively. 'Thatis, the arms 34, 35 and '35 are cylindrical with threaded ends to beinserted in tapped holes at .the upper end of the shaft 33. .'Ihe iinmembers wedged into the slots at the other ends of the radial arms areof sheet bronze.

rlhese elements are assembled by first placing the lower sponged rubbersection 3l) in position in the shell 21 with the cover I0 removed, theninserting the shaft end 33 up through the rubber, .then .threading thearms in position and then inserting the fins in the slots of the arms.The upper rubber section 3| is then placed in the shell 21 and the coverI0 is then inserted and screws .2K6 are tightened. To obtain the desiredfrequency for .the filtering action, the cover I0 is pressed onto therubber to the proper deg-ree, provision being made for tightening thecover at any desired posi-tion by the elongated slots 28 in the shell21. The lower sponged rubber portion 30 extends outside the lower rim ofthe shell, and the lower sides .are cemented to the shell, as well as tothe shaft 313. It has been found that by cementing these portions thereis no tendency of the shaft 33 to leave the rubber or the rubber toleave the shell when the inertia of the microphone exerts a pressure onthe rubber duri-ng movement of the boom.

At the lower portion of the mount is found a yoke 4Z which has a hole inthe upper horizontal portion thereof to accommodate a stud d3 on thelower horizont-al portion of the mem- The yoke 42 is held on the stud bya nut 45 threaded .on the stud 40. The lower ends A of the yoke 42 areconnected to an outer ring 46 of the high frequency filter portion ofthe mount and held thereto by wing nut-and-bolt combinations 41. Aninner ring 50 is attached to the outer ring 416 by means of a flexiblerubber band l interlaced between the two rings.

Extending upwardly from the inner ring are bracket arms 53 :terminatingin a split collar 54 having a tightening scr-ew 55. A spherical typemicrophone 51 having a cur-ved baille 58, as disclosed and .claimed incopending application S. N. 223,237, filed August 5, 1938, is mountedron the bracket arms 53 by tightening the collar 54 about the connectingplug 59 of the microphone. An electrical cable 60 leads from themicrophone to .an amplifier, as is well known in the art.

LErom the above description it will be noted that there are twomechanical filters connected in series between the microphone 51 and'the rod 1, the sponged rubber sections 30 and 3i and the `weigh-t ofthe elements suspended from shaft 33 eliminating the low frequencyvibrations, land th-e stretched rubber bands 5| and the weight of theinner ring and microphone eliminating the high frequency vibrations.Thus, when the extendible end of the boom has a tendency to vibrate at aslow period, the upper lter will prevent the vibrations from affectingthe microphone, while quick and sharp vibrations will be eliminated by`the lower lter. Also, rotation of the microphone by cable I3 vandspring I9 may set up ycertain vibrations which are damped out andprevented from reaching the microphone with sunicient severity to bepicked up thereby.

Another feature of lthe support is the conical shape of the lowerportion `of the upper filter which .prevents reflections of sound wavesand, consequently, reduces echo effects. 'Ilhis support has givenimproved results over other types of resilient Inountings and evenwithout the high frequency portions, has been found to be superico tothe old types. Since lter mounting may be tuned, it is suitable formicrophones diameter yportion attached to one end of said extension andits smaller diameter portion in the direction of said microphone, asuspension shaft for supporting said microphone, a resi-lient materialwithin and interposed between said shell and said suspension shaft andext-ending around said shaft externally of said sheli, and a pluralityof arms embedded in said resilient material and att-ached .to saidshaft.

2. A microphone support in accordance with claim 1 in which said armsextend radially from said microphone support :and are connected to flnmembers extending into sai-d resilient material.

3. A microphone support for minimizing vibration effects on saidmicrophone set up by a flexible extension adapted to be moved foi`adjusting the position of said microphone vcornprising a conical-shapedshell having its larger diameter portion attached to one end of saidextension and its smaller vdiameter portion in the direction of saidmicrophone, a suspension shaft for supporting said microphone, a.resilient material within and interposed between said shell and saidsuspension shaft and extending around sai-d shaft externally of saidshell, a. plurality of arms embedded in said resilient material andattached to said shaft, and a closure for said shell for varying thepressure `on said resilient material in said shell for changing theresonant period of said resilient material.

4. A mechanical lter for supporting a microphone suspended from aflexible support adapted vto be moved for adjusting the position of saidmicrophone comprising a conical-shaped shell connected to one end 4ofsaid support, resilient material positioned in .the lower conicalportion of said shell, a shaft extending through said resilient materialat the other end of sai-d shell for supporting said microphone, a.plurality of removable arms connected to the top portion of said shaftand extending over said resilient material, a second portion ofresilient material mounted above said arms and within the upper portionof said shell, and means for covering said shellv and exerting apressure on said resilient material.

BYRON'F. RYAN.

